U.S. patent application Ser. No. 10/949,373 discloses a method of determining operating voltage of an inverter for overcoming drawbacks of a transformer operating in a single maximum high voltage oscillation in which a cost effective inverter circuit with power factor corrector being installed is shown in FIG. 1 and FIGS. 5A to 5F. A rectification and filter circuit 20 is adapted to convert AC from a power source 10 into DC. A driver 50 is adapted to divide duty cycle of voltage into a plurality of continuous voltage pulses each consisting of lowest input voltage, highest input voltage, and lowest input voltage of DC fed from a power factor corrector 90 connected to the rectification and filter circuit 20. Next, a varying voltage cycle corresponding to each voltage pulse is generated by a transformer 60. Finally, a dark, bright, and dark flashing effect is produced on a load (e.g. CRT) 70 in response to the varying voltage cycle. The Application is able to significantly decrease the cost of a high performance power factor corrector. Further, the Application is able to overcome drawbacks of a prior inverter operating in a single maximum high voltage oscillation since the inverter 60 is operating in a continuous voltage of smooth rising and smooth lowering cycle. As a result, a useful life of the inverter can be prolonged significantly.